Rick's Free Auto Repair Advice

P2138 trouble code

Fix code P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation

accelerator position sensor, P2138, position transducer

Typical accelerator pedal position sensor (APP)

If your vehicle has set a P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation trouble code, read this description to find out what it means.

Many accelerator pedal position sensors actually have two sensors inside. The computer sends a 5-volt reference signal to both sensors and sees the return ground as a sign that the reference signal is reaching the sensors and returning back to the computer. A third wire carries that actual position signal.

To test the APP, the vehicle must meet the following conditions:

System voltage must be greater than 5.23-volts

Ignition switch is in the ACC, RUN, or CRANk position

Trouble codes P0641, P0651, P2120, P2122, P2123, P2125, P2127, and P2128are NOT already stored in the computer

The computer looks at the difference between APP 1 and APP 2. If the two values exceed a predetermined value for more than .5-sec, it will set a P2138 code.

You need a professional shop manual to work on a late model vehicle. And you need access to the latest technical service bulletins so you don’t waste time and money replacing parts that may misbehave due to a manufacturer’s software glitch. Forget about those cheap manuals you find at the auto parts store. They will just lead you astray. Here are the two best online shop manuals around.

©, 2013 Rick Muscoplat


Posted on by Rick Muscoplat

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